Photographic processing method



United States Patent PHOTOGRAPHIC PROCESSING METHOD Martin P. Ostergaard, Jr., Avenel, N.J'., assignor to Gulton Industries, Inc., Metuchen, N .J a corporation of New Jersey Filed Jan. 8, 1957, Ser. No. 633,087

4 Claims. 01. 96-48).

My invention relates to photographic processing methods and in particular to those methods wherein the processing solution is agitated by sonic or ultrasonic waves.

Practically all developing processes for developing the latent image on film, plate or other photographic material require that there be some agitation of the film, plate or other material being processed, during development: Many elaborate mechanical methods employing rockers, motors and other. devices have been designed to accomplish agitation of the solution in the processing tank.

Hand agitation, which is used quite commonly in many photographic establishments, is not consistent in results due to the non-uniformity which is inherent in human beings. In addition, certain hand agitation techniques require that the film be removed from the tank during the procedure and turned 90 and reinserted in the tank. This often results in aerial fog or oxidation because the film is exposed to air during the development process. The developer is also oxidized when the solution in a closed tank is agitated by rocking or rolling the tank by hand or other means because of the bubbles which are formed when the developer, which is agitated, comes in contactwith the air in the tank. This oxidation causes the film to fog and the solution to deteriorate.

The recently introduced nitrogen-burst system of agitation, while it is an improvement over hand agitation methods, also causes oxidation of the solution with the resultant disadvantages. This is due to the fact that the developer solution bubbles because of the introduction of nitrogen into the solution under pressure. When the nitrogen-burst system is employed, the solution in the processing tank builds up a back pressure and blocksthe gas ports; The net result of this action is an uneven distribution of gas entering the tank and nonuniform agitation of the solution.

It can be seen that it is necessary to agitate the processing solutions uniformly so as to obtain a homogeneous solution without oxidation or material change in temperature in order to obtain the best possible film development. Uniform agitation results in complete development of the latent image, better mixing of the chemicals in solution and better dispersal of the chemicals throughout the solution without precipitation of the chemicals out of the solution.

Accordingly, it is a principal object of my invention to provide a method for processing photographic film which produces more uniform mixing of the chemicals in solution and more uniform reaction between the developer and the film than is possible with other methods.

It is a further object of my invention to provide a photographic processing method which will produce a uniform grain pattern on the developed negative.

It is a still further object of my invention to provide a photographic processing method wherein the developed film isfrce of silver grain clumping and ragged edges along its shalp lines.

" ice Itisa still further object of my invention to provide a photographic processing method wherein their is an in.- creasein film speed without increase in grain size.

It is a still further object of my invention to-provide a photographic processing method wherein there is a mini-- mum of surface bubbling of the solution.

Other objects and advantages of my invention will be apparent during the course of the following description.

I have discovered that by agitating the photographic processing solutions with ultrasonic waves 1 am able to obtain denser negatives than are obtained when other agitation methods are used, for the same exposure of the same scene, using the same type film and developer. The grain.- structure is more uniform without increase in grain size. The film is more completely developed and there isn'o' grain clumping caused by undeveloped silver grains. There isan apparent increase in film speed of from five to ten or more times'without increase in grain size when the film is exposed in light whose color temperature is equivalent to that of ordinary daylight.

Theabove results have been obtained, using the teachings of my invention, with ordinary panchromatic (not fine grain). filmdeveloped instandard developer and printed on standard #1 or #2 paper. In a developer which is usually considered to lose 1 F stop from the film s normal rated speed, I have been able to obtain an increase over the rated film speed of from 2 to 4 P stops.

Byway of example and without limitation of the scope of my invention, I have found that excellent development results were obtained when the ultrasonic agitation frequency was 41 kc. and the agitation was applied for 5' secs. out of every minute. I have found that longer agitation times were equally good, provided the temperatureof the transducer did not rise too much. When the transducer is cooled so that it does not overheat the solution, the agitation maybe employed for longer time intervals.

When one quart of solution is used and there is an ultrasonic excitation frequency of 41 kc. applied for five seconds; out of every minute, the temperature rise is only 1.5 F.

I havealso applied ultrasonic agitation to the solution by placing the: transducer in the solution itself and have found that While this method of agitation was much better thanrany other presently known method, it was not as good as that wherein the transducer is mounted on the outside of the tank, preferably at the bottom. There are two' reasons for this action: first, the chemicals, which are not in range of the main lobe of the transducer, ar'enot properly treated and'second, the solutions temperature is not as uniform.

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a front elevational view, partly di agrammatic and partly in cross section of a preferred embodiment of my invention for. developing cut film, plates or film pack sheets,

Figure 2 is a front elevational view, partly diagrammatic and partly in cross section of a further embodiment of. my invention for developing motion picture film,

Figure 3 is a diagrannnatic viewof a further embodiment of my invention for processing color cut film of the reversal type, and

Figure 4 is a diagrammatic view of a further embodiment of my invention illustrating the automatic processing of motion picture film.

In the drawings wherein, for the purpose of illustration, are shown preferred embodiments of my invention, the numeral 10' designates the outer tank which supports inner tank'll. Grommet 12 is of rubber or similar flexible material and serves to insulate 11 from any mechanical shock to which is subjected. 12 likewise serves to insulate 10 from the ultrasonic vibrations which are applied to 1 1. Hanger 13 serves to hold film 14 in solution 15.

Transducer 16 is suitably afiixed to the bottom of 11 (details not shown) and excitation is applied to 16 from ultrasonicgenerator 17. Transducer 16 may be made of natural piezoelectric material, magnetostrictive material, polarized electrostrictive material or any other material which will transform the electrical energy from 17 into sonic or ultrasonic waves. I prefer to use a polarized electrostrictive material composed largely of barium titanate for the active element of transducer 16. Timer 18 contains development timer 18a and interval timer 18b. 18a serves to measure the total development time and may actuate an alarm when the predetermined time has elapsed or in automatic systems may actuate a mechanism which removes the film from the developer and places it in the next solution. 18b serves to control the interval during which excitation is applied to 16 from 17. 18b may be preset so that excitation is applied for any portion of time out of a larger segment of time. I have used 5' seconds of excitation per minute but any other excitation time segment may be preset on 18b. It is also within the contemplation of my invention to utilize a single unit to include the functions of both 18a and 18b.

In operation, the usual developing or other solution is prepared and mixed at the proper temperature and quantity. I have found that when an excitation frequency of 41 kc. is used, it is necessary to maintain the level of 15 in 11 in multiples of 1%", for example: 11 inches. Cut film 14 is placed on holder 13 in the standard manner (details not shown) and 14 is placed in 15. When 14 is so placed, 18a is set for the total processing time 14 is to remain in 15 and 18b is adjusted for excitation interval. 15 is now agitated at an ultrasonic rate for the periods during-which 18b permits excitation to be applied to 16 from 17. When the preset time as determined on 18a has elapsed, an alarm such as a buzzer or similar device is actuated (details not shown) and 14 is ready for removal from 15. I also contemplate the use of automatic machinery with pickup fingers actuated by 18a, which will move the film from one processing step to the next at preset times (details not illustrated).

Figure 2 illustrates a photographic processing tank for developing or processing motion picture or similar film. Tank 21 is suspended in outer tank 20 and is mechanically insulated therefrom by grommet 22. Rails a and 2611 are attached in pairs in tank 21 so as to support film Wheels 25 and 26 respectively. Wheels 25 and 26 are spaced so that two adjacent wheels 26 form an acute angle triangle with wheel 25 which is closest to them and two adjacent wheels 25 likewise form an acute angle triangle with wheel 26 which is closest to them. Film 24 is threaded over reel 27 and around Wheels 25 and 26 as shown in the figure and out of the tank over wheel 28. The film is moved in the direction of the arrows of Figure 2.

Timer 18 operates in the same manner as I have described for the embodiment of Figure 1 with certain additional functions. As described heretofore, timers 18a and 18b may be separate units as illustrated or may be combined in a single unit. Instead of a single transducer as shown in Figure 1, I utilize three transducers 29a, 29b and29c afiixed to the outer surface of the base of tank 21 and actuated by 17 under the control of 18b. However, a single transducer such as is illustrated in Figure 1 may also be used. Likewise, the three transducers of Figure 2 may be employed to replace'the single transducer of Figure 1. Any number of trans ducers may be used and I have chosen one and three for illustrative purposes to demonstrate that one or more may be employed. Transducers 29a, 29b and 290 may be formed of any suitable material. I prefer to use. polarized electrostrictive material composed largely 9f barium titanate. Lead zirconate, lead titanate or combinations of-other such materials may also be employed. I have found that when I use an agitation frequency of 41 kc. and cylindrical transducers composed largely of barium titanate mounted to the bottom of the tank, it is best to have one transducer for each 9 square inches of tank bottom surface.

Solution 23 is prepared in the usual manner and film 24 is threaded on 27, 26, 25 and 28 as shown in Figure 2. 18a and 18b are set and processing begins as described above. When the time preset on 18a has elapsed, the film drive (not shown) is actuated and all the film 24 which has been processed is run out of 21.

Alternatively, 24 may be in continuous motion through 23 such that its velocity and length of travel through 21 together determine the amount of processing time, as-

given by the formula The distance s is a function of the number of wheels 25 and 26 over which 24 is run and the distance between the wheels.

A further alternative method utilizes a frame similar to that supporting wheels 25 and 26 which may be removed from the tank. The film 24 is threaded on 25 and 26 and the combination is placed in solution 23 and processing accomplished as described above for film 14.

Those skilled in the art will realize that while I have described the processes above for development, the ultrasonic agitation techniques taught by my invention will work equally well in short stop, fixing, washing and other processing baths.

Figure 3 illustrates seven baths of the eleven step process for the processing of positive reversal color film. Timer 30 combines the functions of timers 18a and 18b and is preset so that excitation is applied to transducers 16 for a predetermined portion of each time segment and is so designed that no excitation is applied to any transducer 16 if the switches 31a, 32a, 33a etc. corresponding to tanks 31, 32, 33 etc., respectively, are off. 30 is designed so that the time for each tank 31 etc. is counted from the time switch 31a etc. is thrown and a signal associated with tank 31 etc. (not shown) is actuated when the preset time has elapsed. When switch 38 is oif, no excitation is applied to any transducer 16 from 17.

In operation, the film is placed in 31, which contains the developer, and processed for 12 minutes and is agitated for five seconds of every minute. It is then removed from 31 and placed in 32, which contains the rinse, where it remains for three minutes and is agitated as before. It is then placed in a rinse hath (not shown) for one minute without agitation. It is now re-exposed to light for three minutes (not shown). It is next placed in 33, which contains color developer, for 18 minutes during which time it is agitated as described above. Now it is placed in '34, which contains the clearing bath, for three minutes and agitation is carried on as described above. It is then placed in 35, which contains the hardener, for five minutes and is agitated as heretofore. The wash process (not shown) is next and takes five minutes without ultrasonic agitation. The film is now placed in 36, which contains the bleach, for eight minutes and agitation is applied. The next washing (not shown) takes three minutes and no agitation is applied. The film is now placed in 37, which contains the fixer, for five minutes and agitation is applied. The final wash (not shown) is without agitation andconsumes ten minutes.

It is understood that the above-described process is for a particular type of film and other processes lend themselves equally well to the teachings of my invention. A greater or lesser number of steps in the process may be agitated by ultrasonic waves depending on the type of film and type of processing used. I

Figure 4 is an example of a continuous processing unit for motion picture film. Switch 38 controls the application from 17 of ultrasonic excitation to transducers 29a, 29b and 29c of all tanks 40, 41, 42 and 43 while switches 40a, 41a, 42a and 431: control the application from 17 to transducers 29a, 29b and 29c of tanks 40, 41, 42 and 43 respectively. 18b controls the interval during which excitation is applied and 39 actuates the film drive (not shown).

The processing is started by threading a film leader as shown in the arrows of Figure 4 through tanks 40, 41, 42 and 43 to the dryer and take up reels (not shown). The film to be processed is then attached to the leader and is fed off its reel (not shown). The film is then fed through the various stages: tank 40 contains developer; tank 41 contains short stop; tank 42 contains fixer; and tank 43 contains wash. Since the velocity of the film travel is unform,'l keep the time in each solution correct by adjusting the length of travel in the solutions by using more or less rollers 25 and 26 as illustrated in Figure 4. In the example illustrated, development takes 11 minutes, short stop takes three minutes, fixing takes five minutes and washing takes nine minutes. The foregoing is by way of illustration and is not intended to limit the scope of my invention since the times in various solutions may be varied as required. Ultrasonic excitation may be applied to all or some of the solutions which require agitation.

It should be understood that all types of photographic material such as roll film, cut film, strip film, plates, paper or other embodiments may be processed using the teachings of my invention and that the illustration and description of the processing of a particular type of material in the above description is by way of example and not by way of limitation and I do not wish to be limited to the specific examples and embodiments shown and described, for obvious modifications will occur to those skilled in the art without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. The method of procesing exposed photographic materials which comprises placing the material to be processed in the processing solution and subjecting the solution while the material is immersed therein to alternating cycles of agitation and quiescence, the agitation being by means of ultrasonic waves having a frequency of the order of 41 kc. and being carried on for approximately 5 seconds in length out of every minute of time that the material is immersed in the solution.

2. The method of processing photographic materials as described in claim 1 which includes feeding a length of film over a plurality of rollers mounted in the processing solution and moving the film into, through and out of the solution at a predetermined rate.

3. The method of processing photographic materials as described in claim 2 which includes placing the materials sequentially in a plurality of solutions at least one of which is agitated with ultrasonic waves.

4. The method of processing photographic materials as described in claim 1 which includes feeding a length of film sequentially through a plurality of solutions over a plurality of rollers mounted in each of said processing solutions and moving the film into, through and out of said solutions at a predetermined rate, at least one of said solutions being agitated with said ultrasonic waves having a frequency of the order of 41 kc.

References Cited in the file of patent UNITED STATES PATENTS 1,907,252 Debrie May 2, 1933 2,140,438 Webster Dec. 13, 1938 2,349,026 Wildman May 16, 1944 2,529,495 Harlow Nov. 14, 1950 FOREIGN PATENTS 668,780 Germany Dec. 9, 1938 832,398 Germany Feb. 25, 1952 761,488 Germany Feb. 8, 1954 QTHER REFERENCES Photography Theory and Practice, Clerc, 1937. pp. 230, 231. 1 

1. THE METHOD OF PROCESSING EXPOSED PHOTOGRAPHIC MATERIALS WHICH COMPRISES PLACING THE MATERIAL TO BE PROCESSED IN THE PROCESSING SOLUTION AND SUBJECTING THE SOLUTION WHILE THE MATERIAL IS IMMERSED THEREIN TO ALTERNATING CYCLES OF AGITATION AND QUIESCENCE, THE AGITATION BEING BY 